1. Field of the Invention
The present invention relates to a cylinder lock, and, particularly, to a cylinder lock of the type having parallel tumbler pins arranged on a circle coaxial with an axis of the lock.
2. Description of the Prior Art
There are two types of the cylinder locks, one having a rotatable cylinder in which a plurality of tumblers are arranged in the axis direction and the other having a rotatable cylinder in which a plurality of tumblers are arranged on a circle coaxial with the axis. In either case, a pair of pins are provided in each of holes of the two members to be registered at fixed position and by inserting a key thereinto, the tumblers in the rotatable member are shifted axially whereby contact portions of two or more tumblers in the respective holes are simultaneously registered with the contact planes of the stationary member and the rotatable member of the lock to thereby permit rotation relatively between the two members.
Therefore, the number of parts of the conventional cylinder lock such as above is large. And, particularly, when the preciseness of machining of the parts is relatively low, the possibility of undesirable unlocking thereof such as picking is increased because the plurality of the tumblers are inserted into the respective holes. Particularly, the above disadvantages become remarkable for the lock of the type in which the tumblers are arranged axially of the rotatable cylinder. By arranging the tumblers in radial directions, the possibility of the picking may be lowered. However, the latter arrangement renders the structure of the lock complicated.